State of New Jersey v. Kader S. Mustafa

Summary

The Supreme Court of New Jersey held that expert testimony is required for a defendant to invoke the diminished-capacity defense and for a trial court to instruct the jury on that defense. The Court concluded that lay testimony describing bizarre behavior or substance use cannot, without expert interpretation, establish a mental disease or defect affecting the defendant’s ability to form the requisite mens rea. The Court affirmed the denial of Kader S. Mustafa’s requested diminished-capacity instruction and his convictions.

Holdings

1. Expert psychological or psychiatric testimony is required for a defendant to invoke the diminished-capacity defense under N.J.S.A. 2C:4-2.
2. A trial court may not instruct the jury on diminished capacity unless expert testimony is presented.
3. Lay testimony may describe a defendant's observed behavior but cannot, standing alone, establish a mental disease or defect or show that the condition impaired the defendant's ability to form mens rea.

Questions Presented

1. Whether expert testimony is required for a defendant to invoke New Jersey's diminished-capacity defense.
2. Whether expert testimony is required before a trial court may instruct the jury on diminished capacity.
3. Whether lay testimony describing unusual or bizarre behavior, without expert testimony linking a mental disease or defect to the defendant's ability to form mens rea, is sufficient to warrant a diminished-capacity instruction.

Disposition

affirmed